Microwave tunable inductor and associated methods

Abstract

The inductor, preferably a microwave tunable inductor, includes first and second wires twisted together to define a double helix having a first end and second end with a plurality of twists therebetween. First and second terminals are at the first end of the double helix, and a connection at the second end of the double helix electrically connects the first and second wires in series. The inductance is tuned by adjusting a number of twists in the double helix, and the inductance includes a linear tuning range based upon between about 3 to 10 twist for a tuning range of about 7–12 Nanohenries. The inductor can also resonate and filter, and the double helix affords numerous advantages over conventional single helix inductors.

Description

FIELD OF THE INVENTION[0001]The present invention relates to the field of wireless communications, and more particularly, the invention relates to a microwave inductor with linear tuning and related methods.BACKGROUND OF THE INVENTION[0002]Inductors are a fundamental electromagnetic component necessary to a wide variety of devices, such as actuators, relays, motors, DC-to-DC converters and radio frequency (RF) circuits. Inductors having large inductances typically include wires wrapped around a bulk dielectric or ferromagnetic core, and are used in power converters and relays. Radio frequency inductors having small inductances typically are helical coils having an air or ferrite core, and are used in RF circuits and communications equipment.[0003]Inductors for the microwave region can become too small to fabricate and suffer low efficiency and Q values. Conventional RF inductor techniques must often be abandoned. For instance, the ferrite core, or tunable coil slug, is unusable abov...

AI Technical Summary

Benefits of technology

"The present invention provides a practical microwave tunable inductor that can be easily adjusted to tune its inductance. The inductor includes first and second wires twisted together to define a double helix with a plurality of twists therebetween. The inductance can be adjusted by adjusting the twists in the double helix using an inductance tuning tool. The tuning range is linear and the tuning is done in nanohenries. The invention also provides a method of making the inductor and a radio frequency communication device that includes the inductor. The technical effects of the invention include improved performance and reliability of RF circuits and devices."

Problems solved by technology

Inductors for the microwave region can become too small to fabricate and suffer low efficiency and Q values.

For instance, the ferrite core, or tunable coil slug, is unusable above VHF due to eddy current losses in the ferrite.

Even printed spiral inductors have limited usefulness at microwave frequencies, as magnetic field circulation through silicon substrates results in eddy-current loss, and a higher than normal parasitic capacitance.

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